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Non-Maskable Interrupt: Difference between revisions
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A '''non-maskable interrupt''' (NMI) is an interrupt that cannot be ignored. The [[PPU]] normally generates an NMI at the beginning of the [[vertical blanking period]], which is received by the Ricoh CPU. This is the only NMI source on the SNES.<sup>[2]</sup> | A '''non-maskable interrupt''' (NMI) is an interrupt that cannot be ignored. The [[PPU]] normally generates an NMI at the beginning of the [[vertical blanking period]], which is received by the Ricoh CPU. This is the only hardware NMI source on the SNES.<sup>[2]</sup> | ||
[[BRK]] causes a software NMI. | |||
NMIs have higher priority than [[IRQ]]s, but lower priority than Reset. | NMIs have higher priority than [[IRQ]]s, but lower priority than Reset. | ||
Revision as of 14:43, 21 July 2024
A non-maskable interrupt (NMI) is an interrupt that cannot be ignored. The PPU normally generates an NMI at the beginning of the vertical blanking period, which is received by the Ricoh CPU. This is the only hardware NMI source on the SNES.[2]
BRK causes a software NMI.
NMIs have higher priority than IRQs, but lower priority than Reset.
See Also
References
- 7.19 Interrupt Priorities, page 53: https://www.westerndesigncenter.com/wdc/documentation/w65c816s.pdf
- https://problemkaputt.de/fullsnes.htm#snesppuinterrupts
External Links
- snes9x implementation of NMI: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2663